NASA
postponed Discovery's spaceflight earlier today after detecting a leak in a hydrogen gas vent line as the shuttle began fueling up for a planned launch tonight at 9:20 p.m. EDT (0120 GMT March 12).Mike Moses, head of Discovery's mission management team, said engineers will begin inspecting the faulty gas line on Thursday and shuttle officials will meet that afternoon to review launch plans.
Moses said that delaying until March 15 will mean having to cut one spacewalk and three days from Discovery's flight, which was planned to last 14 days and include four spacewalks.
If the mission is delayed even more, to March 16, Discovery astronauts would complete only two of four spacewalks and the mission will run only 10 days, Moses said during a briefing here at NASA's Kennedy Space Center after the launch attempt.
The changes are necessary to make room for a Russian Soyuz spacecraft that is already scheduled to launch toward the International Space Station on March 26. If Discovery doesn't launch by March 17, NASA would have to stand down until after the Soyuz launch and a space station crew change. The next launch window would open on April 7.
"This is life in the space business. Sometimes things happen," said Moses. If Discovery's flight shifts to April, it would likely cause a ripple of delays for NASA's other shuttle launches this year and the planned shift to a larger, six-person crew aboard the space station this May, he added.
At about 2:30 p.m. (1830 GMT) today, about two hours after ground crews began fueling Discovery's massive orange external tank, engineers noticed a leak in a gaseous hydrogen line coming from the tank. The line vents off flammable hydrogen gas, created as the super-cooled liquid hydrogen propellant in the tank boils, in order to keep the tank at the right pressure.
NASA officially scrubbed the launch plan at 2:37 p.m. EDT (1837 GMT).
"Our business requires perfection and our vehicle was not perfect today," said NASA launch director Mike Leinbach.
Mission managers say today's scrub has nothing to do with earlier issues on the shuttle related to fuel control valves in the orbiters main engines. This problem forced Discovery's launch to be delayed about a month from an initial launch date set for Feb. 12.
Engineers ultimately replaced the three valves on Discovery with a set proven to be free of damage, after a similar valve cracked on the shuttle Endeavour during its November 2008 launch. Though that issue posed no problem to Endeavour, mission managers spent weeks testing to make sure Discovery would be safe.
Discovery's seven-astronaut crew, commanded by veteran astronaut Lee Archambault, is due to head toward the International Space Station on NASA's first construction flight of the year. The shuttle will ferry up a final pair of U.S.-built solar wings and the last segment of the space station's backbone-like main truss.
It also is set to deliver Japanese astronaut Koichi Wakata, who will serve as his country's first long-duration astronaut when he stays aboard the station as an Expedition 18 flight engineer for six months. Wakata is set to replace NASA astronaut Sandra Magnus, who will fly home aboard Discovery.
Filling out Discovery's crew are STS-119 pilot Tony Antonelli and mission specialists Joseph Acaba, Steven Swanson, Richard Arnold II and John Phillips.
